Limited or no connectivity. Cannot get an IP address

First here some spec.
Laptop Acer Aspire 1640
Onboeard wireless
Windows XP SP2
Router Linksys WRT54G
Wep inscription

When I try to connect my laptop I see my router and connect to it but it cannot get an IP address so I end up with a limited connection.

Thing I try:
Run Wisockxpfix…..problem remain
Reset Router (unplug/replug)… no result
check WEP key (copy paste it so no mistake)
run configip /all in promtp
run netsh winsock reset in promtp
other PC directly plug in router and working (using one at the moment)
DHCP on auto

So what did I miss My laptop use to work fine before don’t know what else to look
thanks,
Maltz